startup_attach: do not use atoi
startup_attach: do not use atoi

* strace.c (startup_attach): Replace atoi with string_to_uint.

Saruta/strace,cuviper/strace,Saruta/strace,cuviper/strace,Saruta/strace,cuviper/strace,cuviper/strace,Saruta/strace,cuviper/strace,Saruta/strace